Lithiated Aromatic Biopolymer as High-Performance Organic Anodes for Lithium-Ion Storage

Abstract Organic molecule-based electrodes have attracted increasing attention for energy storage systems due to their high structural flexibility and promising sustainability. However, unsatisfactory capacity caused by the inherent low electroconductivity and insufficient Li-accessible active sites of the organics impedes the development of the organic electrodes. Herein we explore the electrochemical properties of pre-lithiated lignin (Li-lig) to demonstrate that a natural aromatic biopolymer after an elaborate chemistry engineering could serve as a high-performance organic anode for lithium-ion batteries, with high initial Coulombic efficiency of beyond 80%, competitive capacity, and excellent cyclability. The full cell with Li-lig//LiFePO4 electrode tested at 0.5 C has a high reversible discharge capacity of 135 mAh g-1 and superior capacity retention of 93.7% even after 600 cycles. The Li-ion storage mechanism can be attributed to an improved electroconductivity after the lithiation, as well as abundant and reversible redox-active sites enabled by the conjugated C=C groups on such organic molecules, which is revealed by computational simulations, in-situ and ex-situ spectral investigations. This work sheds new light on Li-ion storage electrochemistry on biopolymers and promotes the development of green and sustainable lithium-organic batteries.